Arrowsmith by Sinclair Lewis

The Pickerbaugh daughters were always popping into Martin's laboratory. The twins broke test tubes, and made doll tents out of filter paper. Orchid lettered the special posters for her father's Weeks, and the laboratory, she said, was the quietest place in which to work. While Martin stood at his bench he was conscious of her, humming at a table in the corner. They talked, tremendously, and he listened with fatuous enthusiasm to opinions which, had Leora produced them, he would have greeted with "That's a damn silly remark!"

He held a clear, claret-red tube of hemolyzed blood up to the light, thinking half of its color and half of Orchid's ankles as she bent over the table, absurdly patient with her paintbrushes, curling her legs in a fantastic knot.